Display screen or portion thereof of an engine control system with graphical user interface



FIG. 1 is a front view of a display screen or portion thereof of anengine control system with graphical user interface showing a firstembodiment of the new design; and,

FIG. 2 is a front view of a second embodiment thereof.

The text shown in broken lines and other broken lines in the figures,including the display screen itself or portions thereof, are forillustrative purposes only and form no part of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof ofan engine control system with graphical user interface, as shown anddescribed.